Additionally, Prothero’s thesis is both controversial and the sort of newsy question one would expect from a journalist: However appealing we may find the liberal perspective on religion — that all faiths aim at the same god, and their differences can be found only in terminology and language — is it really true that religions are more similar than different?

Prothero’s answer to his own question is decidedly no. “To be fair, those who claim that the world’s religions are one and the same do not deny the undeniable fact that they differ in their particulars. Obviously, Christians do not go on pilgrimage to Mecca, and Muslims do not practice baptism,” he writes in the introduction. “To claim that all religions are the same … is simply to claim that the mathematics of divinity is a matter of the foothills,” or the paths leading up the same mountain.

This approach is “lovely” but “dangerous, disrespectful and untrue,” Prothero says. “For more than a generation we have followed scholars and sages down the rabbit hole into a fantasy world in which all gods are one … In fact, this naive theological groupthink — call it Godthink — has made the world more dangerous by blinding us to the clashes of religions that threaten us worldwide. It is time we climbed out of the rabbit hole and back to reality.”

“After 9/11 and the Holocaust,” Prothero writes, “we need to see the world’s religions as they really are — in all their gore and glory. This includes seeing where they agree and disagree, and not turning a blind eye to their failings.”

While I agree completely with Prothero’s formulation, I think he fails to articulate exactly what is meant by “as they really are.” Too often, he fails to explain when he is oscillating between religion as it is practiced today and religion as it was originally developed.

For example, Prothero states that “You can be a Jew without believing in God,” which is of course partially true. According to whom does he mean that a non-believer can be a Jew, I wonder. If one is born Jewish, some would say (and there are rabbinic statements that indicate) that she or he can never become anything but a Jew, no matter how she or he identifies. It seems to me that folks who are born Jewish, Christian, Muslim, Buddhist or Hindu can choose whether to identify with their faith, and if they choose not to view themselves as members of that faith group, they are not members. If a Jew identifies as Jewish but does not believe in god — which is of course something hard to quantify — then some Jews would say that person is a Jew, while others might cite the Maimonidean article of faith requiring belief in god. Those Jews might view the person as non-Jewish on the basis of belief.

Prothero also claims that “sin” and “salvation” are “Christian ideas.” He continues, “while Muslims and Jews do speak of sin of a sort, neither Islam nor Judaism describes salvation from sin as its aim.” His proof? The jailer who asks Paul in Acts 16:30 what he must do to be saved. “So while it may seem to be an act of generosity to state that Confucians and Buddhists and Muslims and Jews can also be saved, this statement is actually an act of obfuscation. Only Christians seek salvation.”

I would direct Prothero to the Talmud tractate Avodah Zara (“idolatry”) page 18a (English translation here), in which Rabbi Chanina the son of T’radyon, as he is being martyred, assures the executioner that if he accelerates the flames that he will be saved and assured a place in heaven. After the executioner speeds up Chanina’s death, he jumps into the flames and commits suicide. A heavenly voice (literally a “bat kol,” a “feminine voice”) calls out that both the rabbi and the hired killer will go to heaven, which makes such an impression on another rabbi who heard about the story that he weeps and declares: “There are those who acquire a place in heaven on the basis of many years of good deeds (Chanina), and some receive it based on one hour.” There are a number of sources of this sort that indicate that the religious plot may be a good deal thicker than Prothero claims.

Another mistake is a claim about Jewish and Islamic art. While Christians and Hindus say that God assumed human form, Jews and Muslims disagree. “Muslims also join Jews in rejecting visual images of God on the ground that such images, which cannot possibly capture the reality of the divine, tempt us toward idolatry,” he writes. “So while Western art has until modern times been preoccupied with the Christ figure, Islamic art has centered on calligraphy, and particularly on the Arabic letters of the Quran.”

Just as the cliché that Jews have no representational art is hopelessly misguided, so is the claim that Muslims do not. Of course some Muslims do not see it as acceptable to represent Allah or the Prophet Mohammed. In the course of my research for my Arab American News article “Are drawing and painting haraam?” one imam told me that some people in Saudi Arabia frown for their passport photos to express their distaste for the medium. But it was clear from what I heard from other imams and scholars of Islam that the question of Islamic aniconism is a very complicated one.

Hair splitting aside, Prothero’s analysis of mega-churches (none of the 20 largest is in the United Sates), Mormonism (mostly an international religion), Confucianism (“We probably know less about Confucianism than we do about any of the other great religions”) and images of Jesus as a blond-haired white man (like the most famous, Warner Sallman’s 1941 Head of Christ, which is “as out of date as Mr. Rogers“) is very informative and a fun read.